Original Development of a Life Cycle Assessment Methodology for Road Infrastructure in the Nigerian Context

Life cycle assessment of road infrastructure quantifies environmental impacts across material production, construction, maintenance, and end-of-life phases, but existing LCA methodologies are calibrated for European and North American conditions using background inventory data inappropriate for Nigerian material production and transportation contexts. This study develops an original LCA methodology for road infrastructure in the Nigerian context. A process-based LCA framework is developed following ISO 14040/44 standards, with an original Nigerian foreground inventory database constructed for the key road construction and maintenance materials: laterite, quarry aggregate, bitumen, Portland cement, and reinforcing steel. Production process inventory data were collected from primary surveys of five Nigerian quarries, two asphalt plants, and the Dangote Cement production facility. Transportation energy consumption was modelled for Nigerian road haulage conditions. The LCA framework was applied to compare environmental profiles of three pavement typologies: flexible asphalt, concrete slab, and gravel surface, across 50-year life cycles calibrated with Nigerian pavement performance prediction data. Global Warming Potential, acidification, eutrophication, and cumulative energy demand were assessed. Results indicate that life cycle GWP for Nigerian flexible pavement is 2.1 kgCO2e/m2/year, comparable to international studies after Nigerian supply chain adjustment. Bitumen production is the dominant GWP contributor. Rehabilitation frequency is the dominant maintenance impact driver, reinforcing the economic and environmental value of pavement quality preservation. The Nigerian road LCA methodology constitutes an original contribution to sustainable infrastructure science.

Keywords: life cycle assessment, road infrastructure, environmental impact, Nigerian pavement, sustainable construction